From eb9e756b5f5435c0892e411576d5206b3f6f8f74 Mon Sep 17 00:00:00 2001
From: Loek Le Blansch <loek@pipeframe.xyz>
Date: Fri, 18 Oct 2024 14:48:22 +0200
Subject: move audio research to audio design

---
 design.tex | 42 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

(limited to 'design.tex')

diff --git a/design.tex b/design.tex
index a89303a..08ea7cc 100644
--- a/design.tex
+++ b/design.tex
@@ -122,9 +122,47 @@ contains the following classes:\noparbreak
 
 \subsection{Audio}
 
-\subsubsection{Library}
+Since writing a custom real-time audio mixing engine is outside the scope of this
+project\mref and C++ does not provide a built-in cross-platform audio \gls{api}, the
+audio system inside the cr\^epe engine is implemented as a fa\c{c}ade around an
+existing audio library.
+
+\subsubsection{Libraries}
+\label{sec:audio:libs}
+
+This subsection compares various standalone audio libraries for suitability. After
+searching for libraries (search terms: `dynamic/adaptive audio', `real-time audio',
+`audio library', `game audio engine'), several libraries were found. These libraries
+were checked against the audio engine requirements \autocite{crepe:requirements} and
+then tested by writing the same benchmark-style \gls{poc} using the remaining
+qualifying libraries:\noparbreak
+\begin{enumerate}
+	\item Load a background track (Ogg Vorbis)
+	\item Load three short samples (WAV)
+	\item Start the background track
+	\item Play each sample sequentially while pausing and resuming the background track
+	\item Play all samples simultaniously
+	\item Stop all audio and exit
+\end{enumerate}
+
+Of these libraries the following were determined to be unsuitable for use in this
+project:\noparbreak
+\begin{description}
+	\item[FMOD \autocite{lib:fmod}] Is proprietary (violates \cref{req:lib:license}).
+	\item[PortAudio \autocite{lib:portaudio}] Does not handle mixing.
+	\item[miniaudio \autocite{lib:miniaudio}] Tested by implementing a \gls{poc}, but
+		dropped due to very limited codec support (WAV, MP3 and FLAC only); Also does not
+		have an \gls{api} reference (only programming manual).
+	\item[YSE \autocite{lib:yse}] Attempted to write \gls{poc}, but CMake configuration
+		in repository is broken; This project seems to have been abandoned.
+\end{description}
 
-\subsubsection{Fa\c{c}ade}
+The only library that remained after these tests is SoLoud \autocite{lib:soloud}. It
+is Zlib/LibPng licensed and provides a high-level object-oriented C++ \gls{api}.
+\Cref{sec:audio:architecture} describes the fa\c{c}ade written for this library.
+
+\subsubsection{Architecture}
+\label{sec:audio:architecture}
 
 \Cref{fig:class-audio-facade} shows a class diagram of the audio fa\c{c}ade. It
 contains the following classes:
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